Field of the Invention
The present invention relates to a header driven packet switching system and method.
Information communication by packet switching systems has been found satisfactory for communicating data with respect to data processing units, and it is expected that such systems will become widely used.
The field of the header driven packet switching system to which the present invention relates lies between the field of circuit switching systems, in which the available data rate for each line is fixed, and the field of packet switching systems, in which any data rate is used.
In a header driven type packet switching system, data is transmitted as packets and speech paths are circuit switched.
The basic functions required for this switching system are a routing function, for decoding the header of an input packet to transfer it to a destination, and a function for rewriting the header with the virtual call number of a selected line.
Such a prior art header driven type packet switching system is disclosed, for example, in Japanese Unexamined Patent Publication No. 61-127250.
In a conventional header driven type packet switching system, header processing circuits, each of which decodes the header of an input packet, rewrites the information in the header, and transmits a control signal to a switching portion to select an outgoing line for the packet, are provided only in a fixed correspondence with incoming lines of the switching system.
Therefore, when a plurality of packets are continuously transmitted through a particular incoming line, the first packet must be completely processed before the next packet can be processed, and thus the processing of the following packets may be greatly delayed, or those packets may have to be dropped.